(1) Field of the Invention
This invention generally relate to fast-acting valves and more particularly to fast-acting valves adapted for use with projectile launching systems.
(2) Description of the Prior Art
U.S. Letters Pat. No. 4,848,210 discloses an energy storage device for use in association with projectile launching tubes in free flood compartments of a submarine hull. In these systems, a large quantity of water is stored in a reservoir under pressure. A closed valve isolates the reservoir from each launching tube. Opening the valve releases the stored water into the launching tube to eject the projectile.
In order for the water to transfer rapidly and without loss of pressure or force, it is necessary that valve have a large diameter and be fast-acting. A slow-opening valve will impede flow through the valve and limit the projectile ejection velocity.
U.S. Pat. No. 4,848,210 discloses a slide valve for isolating the pressurized storage device from the projectile launching tube. In practice a very complex mechanical system forms this slide valve. When operated rapidly, the components of this mechanical system can increase the level of vibrations and noise that transfer to and emanate from the structure, called "structure-borne vibrations". Generally a pressurized hydraulic cylinder operates the slide valve, and the energy input to the cylinder also can produce vibrations and noise.
U.S. Pat. No. 5,085,122 discloses an energy storage device that continuously communicates with the interior of a launching tube. More specifically, the output port of the energy storage device opens directly into a portion of the launching tube aft of a projectile position. After a projectile is loaded into the launching tube, a fluid operated piston extends transversely to engage and capture the aft end of the projectile. This locks the projectile in the launching tube. Then a pumping operator begins to pump water into the energy storage device, so the full pressure of the water in the energy device acts directly on the aft end of the projectile. Firing occurs when a valve diverts an incremental volume of water from the energy storage device into the fluid operated piston. The piston moves and releases the projectile whereupon the water in the energy storage device expels the projectile. The release piston used in this apparatus is subject to binding and jarring and can generate noise as it operates.
This valve mechanism is used with an "external" launcher, that is, a launcher in which a projectile is loaded from the exterior of a vessel or loaded from the discharge end of the barrel. "Internal" launching systems load the projectile from the breech end of the launching tube or barrel. These barrels may include internal structures, such as keyways, detent mechanisms, sleeves or other devices that are difficult, or in some cases impossible, to seal. Consequently, these launching tube internal structures, or barrel constraints, make it difficult, and in some cases impossible, to adapt such a valve mechanism to an internal launching system.
While U.S. Letters Pat. No. 4,848,210 discloses a system that can be test fired by ejecting a slug of water from the stored energy device through the launching tube and is adapted for repeated rapid firing, testing the apparatus that U.S. Pat. No. 5,085,122 requires the ejection of some mechanical equivalent to the end of the projectile. After either a test object or projectile is fired from the foregoing apparatus, another projectile must be loaded before repressurizing the energy storage device.
In accordance with another alternative, disclosed in co-pending U.S. patent application Ser. No. 08/129,726, filed Sep. 30, 1993, a stored energy device communicates directly with a launching tube. Axially spaced sealing mechanisms disposed in the launching tube on either side of the port engage a cylindrical sealing object that attaches to the aft end of a projectile and spans the sealing mechanisms. Prior to firing, water can be pumped into the energy storage device without ejecting the projectile. On firing, a valve opens to apply water pressure to the aft face of the sealing structure and displace it forward in the launching tube. When the sealing object clears the back sealing mechanism, water begins to flow directly from the energy storage device to the back side of the projectile thereby forcing the sealing object and the projectile out of the launching tube. In this system an incremental water volume from the energy storage device opens the flow port so this launching system does not require added energy. As only the valve contains moving parts, this system minimizes noise production. However, it still produces some noise. It also is not possible to test fire this system without ejecting the sealing object or equivalent structure. Moreover, this valve mechanism is not readily applicable to internal launching systems due to the previously described barrel constraints.